Most of the time Nikon USA service honors the warranty. All they want to see is the original receipt. I don't have personal experience with this, but being a member of this forum for 10 years I have seen numbers of posts on this same topic and rarely, if ever, have I seen a post where service was denied to a second owner.

My suggestion then would be for the O/P to call Nikon and have them clarify their policy.

However, Nikon service seems to be changing (for the worse). Reports of people being denied service for impact damage seems to be the "new norm" and is something you never saw 5 years ago. So who knows, Nikon may start denying service to second owners as per the strict terms of the warranty.

We may not like it but Nikon is not obliged to do so and has never promised any servicing under warranty after transfer to a new owner. I wouldn't compare this to "incidental damage" where - according to those who've been through this - the evidence that the damage is "incidental" is non-existent.